yknoyus....welcome to the community. Don't feel fad about asking questions, we all started somewhere!!
For flashing a ROM, you can go to the upgrade section of the Omnia forum (on top) and there are a lot of threads to look at different ROMs and instructions on how to use them. You should start here:
http://forum.ppcgeeks.com/showthread.php?t=69628 there is a leaked ROM called cc20 that unlocks the GPS. If you are flashing to get GPS capabilities, you have to do that first. After that any ROM goes. You can get a faster device with more memory with some of the base ROMs, and a WM 6.5 ROM that has some cool tweaks.
There is a lot to learn, but (following instructions closely) flashing gets easier!!
There are a vouple volume tweaks in the begining of this thread and the problems thread. I remember seeing them, but never needed them myself. I'll add a direct to them if I see it.
Feel free too ask anything in here, if you can't find it using search there are more than a few people in here happy to help!